International Journal of Scientific Engineering and Technology Volume No.2, Issue No.2, pg : 87-95
(ISSN : 2277-1581) 1 Feb. 2013
Effect of Addition of Flyash on the Properties of Waste Plastic Fibre Reinforced Concrete-an Experimental Investigation Prahallada M.C.1, Prakash K. B.2 1 Professor, Department of Civil Engineering, Christ University Faculty of Engineering, Bangalore560074, Karnataka, INDIA prahallada.mc@christuniversity.in 2 Principal, Government College of Engineering Davalagiri, Haveri-581110, Karnataka, INDIA prakashkb04@rediff.com ABSTRACT The fibre reinforced concrete, which is defined as a composite material consisting of a material of cement mortar or concrete and discontinues discrete, uniformly distributed fibres has gained a wide popularity in the construction industry. The introduction of fibres into the concrete induces many desirable properties to the concrete and such concrete has wide varieties of applications in the field of civil engineering. Many types of fibres like steel, carbon, GI, glass, asbestos fibres can be used for the production of fibre reinforced concrete. The plastic is causing an environmental pollution. The plastic is a non-biodegradable material. It do not undergo decay. To destroy this plastic, if it is burnt, it adds to air pollution by releasing many toxic gases. Thus, for environmentalists, the plastic has become a big headache. Flyash is another industrial waste which is causing environmental pollution. The water in which flysah falls becomes unfit for drinking. The land on which it falls becomes infertile. The air becomes polluted since it spreads into atmosphere and causes lung problems. In this paper an attempts has been made to study the properties of fibre reinforced concrete produced from waste plastic fibres and flyash which are the two environmental pollutions. The strength characteristics of waste plastic fibre reinforced concrete like compressive strength, tensile strength, flexural strength and impact strength are found when the flyash is added in different percentages like 0%, 30%, 50%, 70%, 90%, and 110%. Also the workability characteristic
[Type text]
of waste plastic fibre reinforced concrete with flyash is studied.
Keywords: Waste plastic fibres reinforced concrete, Flyash, Compressive, Tensile, Flexural and Impact strength. 1.0 INTRODUCTION It has been found that the addition of small closely spaced and uniformly distributed fibres to concrete would act as crack arrestors and substantially improve the tensile strength, cracking resistance, impact strength, wear and tear and fatigue resistance. The ductility of the concrete increases by the addition of fibres. Such a composite material is called fibre reinforced concrete. The fibre reinforced concrete is very much attracting the attention of researchers and builders as it has several applications in the civil engineering field. It is used for the production of pre-casting elements like pipes, hulls of ships, railway sleepers, beams, stairways, wall panels, roof panels, roof and floor tiles, manhole covers etc. in its advanced applications FRC can be used in highway payments, airport runway, deck slab construction, water retaining structures, marine structures, blast resistance structures, refractory structures etc. Many types of fibres can be used in the production of FRC. The plastic is becoming a real headache for the environmentalists. The plastic is non biodegradable material. Soil cannot decay it. Water cannot dissolve or disintegrate it. But heat can burn it. But the moment the plastic is burnt, many toxic gases are produced and cause the air pollution. The inhalation of such toxic gases is very dangerous to
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health. Sustainable /safe methods of plastic destruction are not yet invented. 2.0 EXPERIMENTAL WORK 2.1 Materials Used Cement: The cement used in the experimentation was 53-grade ordinary port land cement, which satisfies the requirements of IS: 12269-1987 specifications. Fine aggregates: Locally available sand collected from the bed of river Bhadra was used as fine aggregate. The sand used was having fineness modulus 2.96 and conformed to grading zone-III as per IS: 383-1970 specification. Coarse aggregates: The crushed stone aggregate were collected from the local quarry. The coarse aggregates used in the experimentation were 10mm and down size aggregate and tested as per IS: 383-1970 and 2386-1963 (I, II and III) specifications. The aggregates used were having fineness modulus 1.9. Water: Ordinary potable water free from organic content, turbidity and salts was used for mixing and for curing throughout the investigation. Properties A. Physical properties Fineness-specific surface in m2/kg by Blaine permeability method Compressive strength at 28 days in MN/mm2 B. 1. 2. 3. 4. 5. 6. 7. 8. 9.
Plasticizer: To impart the additional desired properties, a plasticizer (Conplast P-211) was used. The dosage of plasticizer adopted in the investigation was 0.5% (by weight of cement). Fibres: The waste plastic fibres were obtained by cutting waste plastic pots. The waste plastic fibres obtained were all recycled plastics. The plastic fibres were not obtained from granules. The fibres were cut from steel wire cutter and it is labour oriented. Fly ash: The flyash used in the experimentation was obtained from “Harihara polyfibres plant� Harihara(Kumarpatnam). It satisfies the requirements of IS:3812-1981 specification. Physical and chemical properties of flyash are given in Table No 2.1
Permissible limit as per IS: 3812-1981
Results 410
320 (Minimum)
83.33% to 137.28% of the corresponding plain cement mortar cubes
Chemical Properties Silica dioxide (SiO2) Aluminum oxide (Al2O3) Iron or Ferrous oxide (Fe2O3) Magnesium oxide (MgO) Calcium oxide (CaO) Sulphur trioxide (SO3) Sodium oxide (Na2O) Soluble salt Loss of ignition
Not less than 80% of the strength of corresponding plain cement mortar cubes
60.1% 14.77%
SiO2 = 35%(Minimum)SiO2 + Al2O3 + Fe2O3 = 70%(Minimum)
2.84%
5 %( Maximum)
0.6%
-
1.2% 0.58% 1.45% 0.54% 11.34%
2.75%(Maximum) 1.5% (Maximum) 12%(Maximum)
Table 2.1: Physical and chemical properties of fly ash (IS: 3812-1981) * Data taken from the production centre 2.2 EXPERIMENTAL PROCEDURE
The main objective of this experimental investigation is to find out the effect of addition of flyash and replacement of cement by flyash on the workability
and strength characteristics of waste plastic fibre reinforced concrete Concrete was prepared by a mix proportion of 1: 1.374: 2.42 with a W/C ratio of 0.46 which correspond to M30 grade of concrete.
committee-544 on the panels of size 250 x 250 x 30 mm. A mild steel ball weighing 1.216 kg was droped from a height of one meter on the impact specimen,which was kept on the floor. The care was taken to see that the ball was droped at the center point of specimen every time. The number of blows required to cause first crack and final failure were noted. From these numbers of blows, the impact energy was calculated as follows. Impact energy = mghN = w/g x g x h x N = whN (N-m) Where, m = mass of the ball w = weight of the ball =1.216 kg g = acceleration due to gravity h = height of the drop =1m N = average number of blows to cause the failure.
The different percentage addition of flyash was adopted in the experimental programme are 0%, 5%, 10%, 15%, 20%, 25%. Waste plastic fibres having an aspect ratio 30 (thickness = 1mm, length = 30mm and breadth = 5mm) were added in the dry mix at the rate of 0.5% (by volume fraction). All the specimens were cast and tested after 28 days of curing as per IS specifications. When the mix was wet the workability test like slump test, compaction factor test and flow tests were carried out. After 28 days of water curing the specimens were weighed for their density and tested for their strength. The different strength parameters of waste plastic fibre reinforced concrete like compressive strength, tensile strength, flexural strength and impact strength were found for different percentage 3.0 EXPERIMENTAL RESULTS-The following addition/replacement of cement by Micro silica-600 as Tables give the details of the experimental results the case may be. The compressive strength tests were conducted as per IS: 516-1959 on specimens of size 3.1 COMPRESSIVE STRENGTH TEST 150 x 150 x 150 mm. The tensile strength tests were RESULTS - The following Table No 3.1 gives the conducted as per IS: 5816-1999 on specimens of compressive strength test results of waste plastic fibre diameter 150 mm and length 300mm. Indirect tension reinforced concrete with different percentage addition test (Brazilian test) was conducted on tensile strength of flyash test specimens. Flexural strength tests were conducted as per IS: 516-1959 on specimens of size 100 x 100 x 500mm.Two point loading was adopted on a span of 400 mm, while conducting the flexural strength test. The impact strength tests were conducted as per ACI Table 3.1: Compressive strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Percentage addition of flyash
0 (Ref mix)
5
10
15
Specimen identification
Weight of specimen (N)
Density (kN/m3)
A A A B B B C C C D D
80.15 81.13 81.67 81.25 81 80.2 81 81.23 80.32 79.2 79.8
23.74 24.03 24.19 24.07 24 23.76 24 24.06 23.79 23.46 23.64
Average density (kN/m3)
23.99
23.94
23.95
23.63
Failure load (kN)
Compressive strength (MPa)
680 660 690 780 700 795 765 750 780 705 730
30.22 29.33 30.66 34.66 31.11 35.33 34 33.33 34.66 31.33 32.44
Average compressive strength (MPa)
Percentage increase or decrease of compressive strength w. r. t reference mix
30.07
---
33.7
+ 12
33.99
+ 13
32.51
+8
D E E E F F F
20
25
80.32 79.37 79.47 79.48 78.32 79.08 78.72
23.79 23.51 23.54 23.54 23.2 23.43 23.32
23.53
23.32
760 630 680 750 655 660 635
33.77 28 30.22 33.33 29.11 29.33 28.22
30.51
+1
28.88
-4
The above results can be depicted in the form of graph as shown fig 3.1 35
Compressive strength (MPa).
34 33 32 31 30 29 28 27 26 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.1: Variation of compressive strength of waste plastic fibre reinforced concrete with different percentage addition of flyash 3.2 TENSILE STRENGTH TEST RESULTS -The following Table No 3.2 gives the tensile strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Table 3.2: Tensile strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Percentage addition of fly ash 0 (Ref mix)
5
10
15
20
25
Specimen identification
Failure load (kN)
Tensile strength (MPa)
A A A B B B C C C D D D E E E F F F
210 240 230 230 220 240 250 230 220 220 250 210 230 225 220 220 205 230
2.97 3.39 3.25 3.25 3.11 3.39 3.53 3.25 3.11 3.11 3.53 2.97 3.25 3.18 3.11 3.11 2.9 3.25
Average tensile strength (MPa)
Percentage increase or decrease of tensile strength w. r. t reference mix
3.2
---
3.25
+2
3.29
+3
3.2
0
3.18
-1
3.08
-4
The above results can be depicted in the form of graph as shown fig 7.2
3.35
Tensile strength (MPa)
3.3 3.25 3.2 3.15 3.1 3.05 3 2.95 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.2: Variation of tensile strength of waste plastic fibre reinforced concrete with different percentage addition of flyash 3.3 FLEXURAL STRENGTH TEST RESULTS - The following Table No 3.3 gives the flexural strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Table 3.3: Flexural strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Percentage addition of fly ash 0 (Ref mix)
5
10
15
20
25
Specimen identification
Failure load (kN)
Flexural strength (MPa)
A A A B B B C C C D D D E E E F F F
12.2 12.4 12.8 13 12 14 14.8 14 14.4 13.6 15 12.4 14.2 11.6 12.4 10.8 10.2 12
4.88 4.96 5.12 5.2 4.8 5.6 5.92 5.6 5.76 5.44 6 4.96 5.68 4.64 4.96 4.32 4.08 4.8
Average flexural strength (MPa)
Percentage increase or decrease of flexural strength w. r. t reference mix
4.98
---
5.2
+4
5.76
+ 16
5.46
+ 10
5.09
+2
4.4
- 12
The above results can be depicted in the form of graph as shown fig 3.3
7
Flexural strength (MPa).
6 5 4 3 2 1 0 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.3: Variation of flexural strength of waste plastic fibre reinforced concrete with different percentage addition of flyash 3.4 IMPACT STRENGTH TEST RESULTS -The following Table No 3.4 gives the impact strength test results of waste plastic fibre reinforced concrete with different percentage addition of flyash Table 3.4: Impact strength test results of waste plastic reinforced concrete with different percentage addition of fly ash Percentage addition of fly ash
0 (Ref mix)
5
10
15
20
25
Specimen identification
A A A B B B C C C D D D E E E F F F
Number of blows required to cause first crack 5 6 5 4 6 7 8 5 7 6 3 4 2 4 6 2 4 5
final failure 17 14 12 17 18 17 22 24 22 22 21 22 14 11 20 10 10 12
Average number of blows required to cause first final crack failure
Impact strength (N-m) required to cause first final crack failure
5.33
14.33
53.72
144.44
---
---
5.66
17.33
57.05
174.68
+6
+ 21
6.67
22.66
67.23
228.41
+ 25
+ 58
4.33
21.66
43.64
218.33
+ 19
+ 51
4
15
40.32
151.2
+ 25
+5
3.66
10.66
36.89
107.45
+ 31
- 26
The above results can be depicted in the form of graph as shown fig 3.4
Percentage increase or decrease of impact strength w. r. t reference mix first final crack failure
250
First crack Final failure
Impact strength (N-m).
200
150
100
50
0 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.4: Variation of impact strength of waste plastic fibre reinforced concrete with different percentage addition of flyash 3.5 WORKABILITY TEST RESULTS -The following Table No 3.5 gives the overall results of workability of waste plastic fibre reinforced concrete with different percentage addition of flyash Table 3.5: Workability test results of waste plastic reinforced concrete with different percentage addition of flyash Percentage Workability through addition Slump Compaction Percentage of fly ash (mm) factor flow 0 (Ref 0 0.87 12.38 mix) 5 0 0.83 12.53 10 0 0.89 11.02 15 0 0.86 11.67 20 0 0.83 10.91 25 0 0.84 10.05 The above results can be depicted in the form of graphs as shown in fig. 3.5 to 3.7 1 0.9 0.8
Slump (mm).
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.5: Variation slump of waste plastic fibre reinforced concrete with different percentage addition of flyash
0.9 0.89
Compaction factor.
0.88 0.87 0.86 0.85 0.84 0.83 0.82 0.81 0.8 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.6: Variation of compaction factor of waste plastic fibre reinforced concrete with different percentage addition of flyash 14 12
Percentage flow
10 8 6 4 2 0 0
5
10
15
20
25
Percentage addition of flyash
Fig 3.7: Variation of percentage flow of waste plastic fibre reinforced concrete with different percentage addition of flyash
Based on the experimental results the following observations were made
10% addition of flyash the tensile strength starts decreasing. Thus, the waste plastic fibre reinforced concrete shows a higher tensile strength when 10% fly ash is added and the percentage increase in the tensile strength is 3%
1. It has been observed that the waste plastic fibre reinforced concrete show an increasing trend in the compressive strength upto 10% addition of fly ash into it. After 10% addition of fly ash the compressive strength starts decreasing. Thus, the waste plastic fibre reinforced concrete shows a higher compressive strength when 10% fly ash is added and the percentage increase in the compressive strength is 13%
5. It has been observed that the waste plastic fibre reinforced concrete show an increasing trend in the flexural strength upto 10% addition of flyash into it. After 10% addition of fly ash the flexural strength starts decreasing. Thus, the waste plastic fibre reinforced concrete shows a higher flexural strength when 10% fly ash is added and the percentage increase in the flexural strength is 16%
4. It has been observed that the waste plastic fibre reinforced concrete show an increasing trend in the tensile strength upto 10% addition of fly ash into it. After
2. It has been observed that the waste plastic fibre reinforced concrete show an increasing trend in the impact strength upto 10% addition of flyash into it. After 10% addition of fly ash the impact strength starts
4.0 OBSERVATIONS AND DISCUSSIONS
decreasing. Thus, the waste plastic fibre reinforced concrete shows higher impact strength when 10% flyash is added and the percentage increase in the impact strength for first crack is 25% and final failure is 58% respectively. This may be due to the fact that 10% addition of fly ash may induce maximum workability through which a thorough compaction can be achieved which aids in higher strengths. Also it may be due to the fact that 10% addition fly ash may fill all the cavities and induce right pozzolonic reaction. Thus it can be concluded that 10% flyash addition will induce higher strength properties to waste plastic fibre reinforced concrete. 3. It has been observed that the maximum workability is achieved when 10% of flyash is added. After 10% addition of flyash the workability decreases. The concrete becomes stiff as the percentage of flyash increases beyond 10%. This may be due to the fact that 10% addition of flyash may act as ball bearings thus reducing the friction and enhancing the workability. Thus it can be concluded that 10% addition of flyash yield good workability in waste plastic fibre reinforced concrete. 5.0 CONCLUSIONS 1. It can be concluded that 10% addition of flyash will induce higher strength properties and good workability properties to waste plastic fibre reinforced concrete. 2. Thus flyash can be used in the production of waste plastic fibre reinforced concrete
ACKNOWLEDGEMENTS The authors would like to thank Vice-Chancellor, Christ University, Fr. Benny Thomas, Director and Dr. Iven Jose, Associate Dean, Christ University Faculty of Engineering, Bangalore for their constant encouragement.
REFERENCES [1] Alen Petersonn “Superplasticizers and concrete”, Indian concrete Journal May 1981
flowing
[2] Ghosh S. N “Advances in cement Technology”, First edition 1981 pub-pergaman press library of congress [3] Nevellie A.M “Properties of Concrete”, First edition 1981 pub-The English language book society [4] Praksah K.B and Krishanswamy K. T. “Superplasticizers A must for High Strength concrete”, New Building Materials and Construction World Oct 1996 [5] Dr. Swamy R N “FRC - Mechanics and Properties and applications”, Indian Concrete Journal January 1974